HK1020799A - Magnetic core-coil assembly for spark ignition systems - Google Patents

Description

Magnetic core-coil assembly for spark ignition system

Reference to related applications

This application is a continuation-in-part application of U.S. patent application No. 08/639,498 filed on 29/4/1996.

Background

1. Field of the invention

The present invention relates to a spark ignition system for an internal combustion engine; and more particularly to a spark ignition system that improves engine system performance, reduces the size of magnetic components within the spark ignition transformer, and can be manufactured in a commercially available manner.

2. Description of the Prior Art

In spark-ignited internal combustion engines, a flyback transformer is typically used to generate a high voltage to create an arc across the spark plug gap to ignite the fuel and air mixture. The timing of the ignition spark is critical to achieve optimal fuel economy and to emit less environmentally harmful gases. Too late an ignition event can result in a loss of engine power and efficiency. Premature ignition events can cause knock (often referred to as "knocking") which can lead to harmful premature ignition and subsequent engine damage. The correct timing of ignition depends on engine speed and load. For optimum performance, different ignition timings are often required for each cylinder of an engine. By providing a spark ignition transformer for each spark plug, different ignition timings for the respective cylinders can be obtained.

To improve engine efficiency and eliminate some of the problems associated with improper spark timing, some engines are equipped with microprocessor-controlled systems that include sensors for sensing engine speed, intake air temperature and pressure, engine temperature, oxygen content in the exhaust gases, and detecting knock. A knock sensor is essentially an electromechanical sensor that is not sensitive enough to detect knock over the entire engine speed and load range. Determining the correct ignition timing with a microprocessor does not always provide the best engine performance. There is a need for a better detection of "knock".

During initial operation of a cold engine and during idling or over-idling, large amounts of harmful exhaust gases are produced. The research shows that: in the two working phases of the engine, the rapid ignition of the spark plug is adopted for each ignition action, so that the emission of harmful gases can be reduced. Accordingly, a spark ignition transformer that can be charged quickly and discharged very quickly is desirable.

In a coil-on-ignition spark plug (CPP) ignition configuration, a spark ignition transformer is mounted directly to the end of the spark plug, eliminating the need for a high voltage electrical cord, thus achieving a method of improving spark plug ignition timing for an internal combustion engine. An example of a CPP firing configuration is disclosed in U.S. Pat. No. 4,846,129 (hereinafter the "Noble patent"). The physical diameter of the spark ignition transformer must be such that it fits within the same engine duct in which the spark plug is installed. To achieve the desired testing goals of the Noble patent, the patentee discloses an indirect method of using a ferrite core. Ideally, the magnetic properties of the spark ignition transformer are sufficient to detect spark conditions within the combustion chamber throughout engine operation. Clearly, a new type of ignition transformer is needed for accurate engine testing.

The misfire phenomenon of the engine increases the emission of harmful gases. Many cold starts that do not have sufficient heat that occur in the spark plug insulator in the combustion chamber can result in misfire due to carbon build-up on the insulator. Conductive carbon deposits reduce the voltage increase obtained in a firing event. The spark ignition transformer capable of increasing the voltage very quickly can minimize the misfire caused by carbon deposition.

To achieve the spark ignition performance required for successful ignition and engine testing as disclosed by Noble, while reducing engine misfire due to spark plug carbon buildup, the spark ignition transformer core material must have a permeability, must not be magnetically saturated during operation, and must have low magnetic losses. Compromise of these desirable characteristics can narrow the source of suitable core material. Possible choices for core materials in view of the targeted cost of automotive spark ignition systems include: silicon steel, ferrite, and iron-based amorphous metals. The conventional silicon steel commonly used in the current transformer core is relatively cheap, but its magnetic loss is too high. Silicon steel with lower thickness and lower magnetic losses is also too expensive. Ferrites are inexpensive, but their saturation induction is typically less than 0.5T, and the curie temperature at which the induction of the core approaches zero is about 200 ℃. Since the upper operating temperature of the spark ignition transformer is assumed to be about 180 ℃, the above-mentioned curie temperature is too low. The iron-based amorphous metal has a low magnetic loss and a high saturation induction of 1.5T or more, but it shows a relatively high magnetic permeability. There is a need for an iron-based amorphous metal suitable for achieving the permeability levels of spark ignition transformers. With this material, a coil of toroidal design can be manufactured which meets the required output conditions and the actual dimensional requirements. The size requirements of the spark plug may limit the types of structures that can be used. Typical dimensional requirements for the insulated coil assembly are: the diameter is less than 25mm, and the length is less than 150 mm. Also, these coil assemblies must be connected to the high voltage end of the spark plug and the external ground connection and provide sufficient insulation to prevent arc cross-over. They must also have the ability to couple high currents to the primary coil, which is typically located at the top of the coil.

Summary of The Invention

The present invention provides a magnetic core coil assembly for a coil-on-ignition spark plug (CPP) spark ignition transformer that produces a rapid voltage rise and produces a signal that accurately reflects the voltage waveform of the ignition event. In general, the magnetic core-coil assembly includes a magnetic core made of a ferromagnetic amorphous metal alloy. The core-coil assembly has a single primary coil for low voltage excitation and a secondary coil for high voltage output. The assembly also has a secondary coil comprising a plurality of iron core subassemblies which are simultaneously excited by a common primary coil. The core subassemblies are adapted to generate an additional secondary voltage upon excitation and delivered to the spark plug. With the above structure, the core-coil assembly has the following capabilities: generating a high voltage in the secondary winding for a short period of time after excitation; and (ii) detecting a spark ignition condition within the combustion chamber to control the ignition event.

More specifically, the core is made of an amorphous ferromagnetic material with low core loss and permeability (about 100-. Such magnetic properties are particularly suitable for rapidly igniting the spark plug during a combustion cycle. The misfire of the engine due to carbon deposit can be minimized. Furthermore, the energy from the coil to the spark plug can be transferred efficiently, so that the energy remaining in the core after the discharge is very small. The low resistance annular design (< 100 ohms) allows most of the energy to be dissipated in the spark plug rather than in the secondary coil wire. Efficient energy transfer allows the core to monitor the waveform of the ignition event in an accurate manner. When a magnetic core material is wound into a cylindrical body having a primary coil and a secondary coil wire to form a toroidal transformer, a signal generated therefrom can reflect the waveform of an ignition voltage more accurately than that of a core having a large magnetic leakage. A multiple annular assembly is formed which stores energy within each subassembly by means of a common primary coil which is induced by the subassembly and controlled by its magnetic properties. When the primary current drops rapidly, the secondary voltage rises rapidly. The secondary voltage across each annular subassembly rises rapidly and is summed with the subassembly voltage according to the total flux variation of the system. This allows to combine several sub-assembly units wound by the existing toroidal winding techniques, thus obtaining a single assembly with excellent performance. It is inconvenient and uneconomical to manufacture a single assembly consisting of a single long loop coil using a conventional loop coil winding machine.

In a preferred embodiment of the coil-core assembly, the assembly is encapsulated (sealed) within a housing to prevent high voltage arcing. In operation, the assembly needs to keep its interior from approaching open circuit voltage for a long period of time under widely varying environmental conditions. The open circuit voltage is the highest voltage encountered by the system. This open circuit voltage must be avoided in the case of years of operation with temperature variations in the range-40 ℃ to +150 ℃. It is also desirable that the assembly be relatively well-tolerated by the chemicals typically encountered when applied in automotive applications.

Automotive manufacturers have previously adopted a variety of packaging and housing materials. For automotive applications, the potting compound, the housing material, and the sealing article may be thermally matched (i.e., have approximately the same coefficient of thermal expansion CTE) by the addition of fillers, such as glass fibers and/or mineral materials, within the potting and housing materials. The aim is to reduce the stresses and strains between the various materials in the system also in the case of extreme operating temperatures. The addition of glass fibers and/or minerals generally increases the dielectric constant of the material. The common encapsulating compound is two-componentThe anhydrous epoxy resin formulation of (a) is excellent in adhesion to the housing and its internal components, and has high-temperature electrical properties and excellent thermal shock resistance. To match the CTE of the material over a wide temperature range, epoxy resins are formulated to have a glass transition temperature (T) equal to the practical maximum operating temperature_g). An example of such an epoxy resin may be EP-697, manufactured by Thermoset. The housing material is typically made of a strong thermoplastic polyester filled with glass fibers having a high T_gAnd CTE matched epoxy. One suitable shell material that has been found is sold under the trademark Vandar by Hoescht Celanese. Filling such a thermoplastic polyester with glass and/or mineral can result in a harder, stronger material.

This "pencil" type coil structure differs from the existing coil structure in that it has a smaller diameter and is longer than a typical squat type coil. This large length/diameter ratio can create large internal stresses within the coil if the CTE match is not perfect over the entire temperature range. It is difficult to achieve this matching of different materials in the operating range of approximately 200 c. In one common design, the working member (the annulus cup) is located very close to the inner wall of the housing. Because the cup and the inner wall of the shell have a large area, the potting compound can solidify the components together, bonding the outer sides of the components to the inner wall. In a toroidally wound unit, a significant portion of the potting compound fills the gap between the bottom and top of the core-coil assembly through the center of the core-coil section. The diameter of this column is related to the design of the ring and the winding equipment. Such a column formed of potting compound and the ring cup present a large shear force due to the relatively long length of the column and the sealing of the bottom of the core-coil assembly. Two-component epoxy potting compounds are generally very hard and inflexible and bond very well to the housing plastic. In this case, the high shear forces may cause the outer material of the shell to delaminate from the body of material, thereby forming a crack that bridges the primary and secondary windings. This is because the resin is concentrated on the surface of the shell, while the lower layer thereof has a glass fiber or mineral component. These two components are very hard, but the annular cups formed from the shell material generally have a low yield strength so that they first delaminate. This causes an internal arc that shorts the primary and secondary coils before a useful voltage is obtained from the core-coil assembly. The stresses that cause this problem are generally due to the very large operating temperature range of the core coil (-40 ℃ to +150 ℃) and the large temperature gradients that result from thermal shock.

One solution to this problem is to utilize a more compliant variation of the packaging and housing materials. Because of their better yield and deformability, these types of materials generate much less shear forces. The potting compound which meets this requirement is a two-component elastomeric polyurethane material, such as Epic S7207. This is a two-component elastomeric polyurethane material designed to encapsulate electronic components. It has a high dielectric strength and a moderate shore a hardness, and has a low dielectric constant. T of such a material_gIs about-25 ℃ and has a CTE of 209X 10^-6cm/cm/. degree.C. Such materials are soft, compliant and elastically deformable. Such materials generally have a lower T than two-component epoxy resins_gAnd due to being at T_gOperating above temperature thus has a much larger CTE. Another encapsulant is a two-part silicone rubber compound such as S-1284 sold by Castall. One casing material with better thermal performance and compliance is Lemalloy PX603Y, manufactured by Mitsubishi Engineering Plastics. Lemalloy is a PPE/PP (Polyphenylene ether)/polypropylene) blend that is flexible and has a low dielectric constant, excellent electrical properties, excellent chemical resistance, and injection moldability. This material is only very slightly crystalline but exhibits good and stable mechanical properties. Such materials and include polymethylpentene/polyolefin blends and polycycloolefinsOther similar materials, including polyolefin blends, are polymers that can be used at high temperatures. Lemalloy material encapsulating compounds adhere well to each other when the surfaces have been appropriately prepared and plasma treated prior to encapsulation. Core-coil assemblies made from these materials are able to withstand thermal shock cycles from-40 ℃ to +150 ℃ with the pencil-type coil configuration, even when the CTE match between the components is poor.

Brief description of the drawings

Other advantages of the present invention will become apparent from the following description of the preferred embodiments of the invention, which is to be read in connection with the accompanying drawings.

FIG. 1 is a connection method and assembly flow diagram of connectors for manufacturing a stacked arrangement of coil assemblies of the present invention;

FIG. 2A is an assembled view showing the side and top aspects of the stacked configuration;

FIG. 2B is an assembly view showing the side and top aspects of the stacked configuration after packaging;

fig. 3 is a graph of the number of ampere-turns on the primary winding and the output voltage across the secondary winding shown in fig. 1.

Description of the preferred embodiments

Referring to fig. 1, the magnetic core-coil assembly 34 includes a magnetic core 10 made of a ferromagnetic amorphous metal alloy. The core-coil assembly 34 has a single primary coil 36 for low voltage excitation and a secondary coil 20 for high voltage output. The core-coil assembly 34 also has a secondary coil 20 comprising a plurality of core subassemblies (annular units) 32, which are simultaneously excited by a common primary coil 36. When the core subassemblies are energized, they may produce a secondary voltage that is summed and delivered to the spark plug. With this configuration, the core-coil assembly 34 has the following capabilities: a high voltage is generated in the secondary winding 20 for a short period of time after excitation; and (ii) detecting a spark ignition condition within the combustion chamber to control the ignition event.

The magnetic core 10 is based on an amorphous metal with high magnetic induction, including iron-based alloys. Magnetic cores are known in two forms, namely gapped and non-gapped, both of which are referred to as cores 10. The gapped core has discrete magnetic portions in a continuous magnetic circuit. An example of such a core 10 is a toroidal magnetic core with a small gap commonly referred to as an air gap. When the required permeability is much lower than the permeability of the wound magnetic core itself, a gap-type structure is suitable. The air gap portion of the magnetic circuit may reduce the overall permeability. The non-gapped core has a permeability similar to that of the air gap type, but it is physically continuous, having a structure similar to that of a generally toroidal magnetic core. The occurrence of uniformly distributed air gaps within the non-gapped core 10 has led to the term "distributed-gap-core". Both the gapped and non-gapped designs work in the core-coil assembly 34, and the two designs can be interchanged as long as the effective permeability falls within the desired range. The use of a non-gapped core 10 is to demonstrate the principles of the standard design of the present invention, but the invention is not limited to the use of non-gapped core materials.

The non-gap type iron core 10 is made of amorphous metal based on iron alloy, and is processed such that: the permeability is between 100 and 500, measured at a frequency of about 1 kHz. The leakage flux from a distributed gap core is much smaller than the leakage flux from a gap core, which reduces the effect of unwanted radio frequencies on the surrounding environment. In addition, since the non-gap type iron core has a closed magnetic circuit, the signal-to-noise ratio of the non-gap type iron core is much higher than that of the gap type iron core, so that the non-gap type iron core is particularly suitable for being used as a signal transformer for checking the combustion process of an engine. With a non-gap type coil in which the ampere-turn number of the primary coil 36 is less than 60 and the number of turns of the secondary coil 20 is about 110 to 160, an output voltage of 10kV or more can be obtained at the secondary coil 20.

Open circuit output voltages in excess of 25Kv can be achieved with ampere turns < 180. The coil that has demonstrated in advance is made by banded amorphous metal material, and these banded metal material are the coiling and become a plurality of right angle cylinder body, and its internal diameter is 12mm, and the external diameter is 17mm, and the height is 15.6mm, and these small cylinder body superposes into the round cylinder body that an effective cylinder height is 80 mm. The height of the individual cylinders may vary from about 80mm to 10mm, as long as the overall length meets the requirements of the system. The dimensions in this example need not be strictly adhered to. There may be a large design variation space according to different input and output requirements. The resulting right-angled cylindrical shape forms an elongated toroidal core. The insulation between the core and the wire is achieved by means of a heat-resistant moldable plastic which is also folded into a coil form to facilitate the winding of the toroidal coil. And winding the secondary coil with 110 and 160 turns by adopting a thin conducting wire. Since the output voltage of the coils can exceed 25kV (indicating that the coil-to-coil voltage is in the range of 200 volts), the wires cannot overlap significantly. The best performing coil has approximately 300 degrees of wire evenly spaced over the loops. The remaining 60 degrees are used for the primary coil. One drawback of this type of coil is the length/diameter ratio of the toroid and the number of secondary turns for normal operation. The fixture used to wind these coils requires handling very thin wires (typically 39 gauge or higher) without significant wire overlap and damage during the winding operation. Conventional ring coil winding machines (universal type) cannot wind coils around this length/diameter ratio due to their inherent design. A variant design based on a shuttle pushed through the core and then around its periphery is required and specifically tailored. Usually, winding these coils is time consuming. Thus, while this elongated loop design is very functional, it is difficult to produce in a commercially attractive, low cost, high volume manner.

There is a variation of the design that breaks down the original design into a smaller composite structure in which the components can be conventionally wound using existing coil winding machines. The design is as follows: the core portions are made of a core material that is dimensionally manageable and based on the same amorphous metal. The design is realized by that: an insulating cup 12 is formed into which the core 10 is inserted and the subassembly 30 is handled as a core and wound into a toroidal coil 32. The same number of secondary winding turns 14 as in the original design is required. The resulting assembly 34 may be constructed of a sufficient number (1 or more) of structures 32 to achieve a widely varying desired output characteristic. Every other ring unit 32 must be counter-wound. This allows the output voltages to be summed. An exemplary configuration 34 may include the first ring unit 16 wound counterclockwise (ccw) from an output wire 24, the output wire 24 being the output end of the final coil assembly 34. The second annular unit 18 is wound clockwise (cw) and is stacked on top of the first annular unit 16 with a spacer 28 therebetween to provide sufficient insulation. The lower lead 42 of the second annular element 18 is connected to the upper lead of the first annular element 16. The next annular unit 22 will be wound counterclockwise and stacked on top of the first two annular units 16, 18 with a spacer 28 for insulation therebetween. The lower lead 46 of the third ring unit is connected to the upper lead 44 of the second ring unit. The total number of ring units 32 is determined according to design criteria and actual size requirements. The last upper lead 26 forms the other output of the core-coil assembly 34. The secondary coil 14 of each annular unit 32 is individually wound covering about 300 degrees of the full 360 degrees of the annular member. The annular cells 32 are stacked such that the open 60 degree area of each annular cell 32 is vertically aligned. A common primary coil 36 is wound through the core-coil assembly 34. This is the principle of so-called stacked coils.

The voltage distribution around the original coil design is similar to an autotransformer, i.e., 0 volts at the first turn and full voltage at the last turn. This is effective over the entire height of the coil structure. The primary coil is insulated from each secondary coil and is located in the 60 degree free region in the middle of the wound loop. These lines are essentially low potential due to the low voltage drive used on the primary coil. The highest voltage stress occurs at each point closest to the high voltage output and the primary, between the secondary and secondary, and between the secondary and the core. The highest electric field stress point is below the inside of the ring along the length direction, and the electric field is strengthened at the top and the bottom of the inside of the coil. The voltage distribution of the stacked (stackercon) is slightly different. Each core-coil unit 32 has the same autotransformer type distribution, but the stacked distribution of core-coil assemblies 34 may be separated by the number of ring units 32. If there are 3 ring units 32 in the stacked core-coil assembly 34, the voltage of the bottom ring unit 16 is V to 2/3V, the voltage of the second ring unit 18 is 2/3V to 1/3V, and the voltage of the top ring unit 22 is 1/3V to 0V. Such a configuration reduces the high-pressure stress region.

Another problem with the original coil design is the capacitive coupling of the output to the outside through the insulator housing. The waveform of the output voltage has a short pulse component (typically with a pulse width of 1-3 microseconds and with a rise time of 500 ns) and a much longer low level output component (typically a pulse width of 100-150 microseconds). The short pulse output component is capacitively coupled to the outside through the wall of the insulator. By observing the corona phenomenon on the housing, the effect of the autotransformer can be noticed. Since a local shunt is formed through the housing to earth ground, the capacitive coupling can take part of the output to the spark plug. This effect is only problematic in the very high voltage range, since the open circuit voltage of the device is then reduced by the corona discharge. The stacked voltage distribution is different and it is possible to place the highest voltage part at the top or bottom of the core-coil assembly 34 depending on the structure of the ground. The advantage of this design is that the high voltage section can be placed deep within the spark plug pocket. For a 3-layer coil unit, the voltage at the top of the core-coil assembly 34 is only 1/3V at the highest.

Preparing a plurality of cast magnetic iron cores made of iron-based amorphous metal materials with saturation magnetic induction intensity exceeding 1.5T. These cores are cylindrical with a cylindrical height of about 15.6mm and outer and inner diameters of about 17mm and 12mm, respectively. The iron core is heat-treated without applying an external magnetic field. Fig. 1 is a flow chart showing the structure of three stacked core-coil assemblies 34. These cores 10 are inserted in a plastic insulating cup 12 resistant to high temperatures. Several of the units 30 are processed on a toroidal coil winding machine to wind 110 to 160 turns of copper wire clockwise to form a secondary coil 14 and to wind the other toroidal units counterclockwise. The first ring element 16 (bottom) is wound counter-clockwise with the lower lead 24 serving as the system output lead. The second annular element 18 is wound clockwise with its lower lead connected to the upper lead 40 of the first annular element 16. The third annular element 22 is wound counterclockwise with its lower lead 46 connected to the upper lead 44 of the second annular element 18. The upper lead 26 of the third ring element 22 is used as a ground lead. The plastic spacer between the ring units 16, 18, 11 serves as a voltage insulator. The non-winding areas of the ring unit 32 are vertically aligned. A common primary coil 36 is wound through the core-coil assembly 34 in the area where it is not wound. The core-coil assembly 34 is housed in a high temperature resistant plastic housing with lead holes therein. The assembly is then vacuum molded with an acceptable potting compound to form a high voltage insulation manifold. The encapsulating material may be of many types. The basic requirements of the potting compound are: has sufficient insulation strength; adhere well to all other materials within the structure; can survive in strict environmental conditions such as recycling, temperature, impact, vibration and the like. It is also desirable that the potting compound have a lower dielectric constant and a lower loss tangent. The housing material should be injection moldable, inexpensive, have a low loss tangent with a low dielectric constant, and survive the same environmental conditions as the encapsulant material.

Fig. 2A is a side view and a top view of the stacked assembly 34 prior to encapsulation. Fig. 2B is a side view and a top view of the stacked assembly 34 encapsulated into the final assembly 100. The stack 34 is placed within a hollow tubular housing 50 made of the aforementioned polymeric material having high temperature service characteristics. The base 55 has a connector 70 for attachment to the spark plug and sealing to the housing 50. The output lead 24 is connected to the connector 70 to form an electrical path to the spark plug. The output lead 26 may be routed out of the assembly 100 and connected to an engine ground point, a return point of the spark plug, or other similar point to form a closed circuit for the secondary winding which is vented through the spark plug gap. The potting compound 60 is injected into the housing 50 according to the manufacturer's recommended specifications. The characteristics of the encapsulating compound are discussed above. The primary coil wire 36 extends away from the housing and enclosure body, which may be used as the primary coil of the core-coil assembly. The annular bowl 12, shell 50 and bottom 55 are made of the shell material described above. To promote bonding of potting compound 60 to housing 50, annular bowl 12, bottom 55, and other internal components are subjected to a plasma cleaning process prior to potting, as described by the manufacturer of the plasma cleaner.

The primary coil 36 is supplied with a current that rapidly reaches (but is not limited to) 60 amps in a time period of 25 to 100 microseconds. Figure 3 shows the voltage output obtained when the primary current is rapidly switched off at a given peak ampere-turn. The charging time is typically < 120 microseconds with a 12 volt voltage on the primary switching system. The output voltage has a FWHM (full width at half the pulse height) which is typically shorter with a pulse width of about 1.5 microseconds and a longer low level pulse back porch lasting about 100 microseconds. Therefore, in the magnetic core-coil assembly 34, a high voltage of 10kV or more can be repeatedly generated in a time interval of less than 150 microseconds. This feature is necessary to achieve the rapid multiple ignition effect described above. In addition, the rapid rise of the voltage in the secondary coil can reduce the phenomenon of engine misfire caused by carbon deposit.

In addition to having the advantages described above with respect to spark ignition, the core assembly of the present invention may also serve as an engine testing device. Since the magnetic core 10 of the present invention has low leakage flux, the waveform of the primary coil voltage can faithfully reflect what occurs in the accumulated sub-coils. During each rapid flux change that results in a high voltage being generated in the secondary winding, the primary winding voltage is analyzed during ignition to obtain the correct ignition characteristics. The obtained data is sent to an ignition control system. Thus, the core-coil assembly 34 of the present invention may eliminate the need for additional magnetic elements such as those required in the Noble patents (where the core is made of a ferromagnetic material).

The present invention may be more fully understood in light of the following examples. The particular conditions, materials, proportions and reported data set forth herein are illustrative of the principles and applications of the present invention and are not intended to limit the scope of the invention in any way.

Examples of the present invention

An amorphous iron-based metal ribbon having a width of about 15.6mm and a thickness of about 20 μm was wound onto a machined stainless steel mandrel and spot welded to the inner and outer diameters of the mandrel to maintain a certain tolerance. The mandrel defines an inner diameter of 12mm and the outer diameter is selected to be 17 mm. Each iron core was subjected to annealing treatment in a nitrogen atmosphere at a temperature of 430 to 450 ℃ for a heat treatment time of 2 to 16 hours. The annealed core was placed in an insulating cup and wound 140 turns with thin insulated copper wire on a toroidal coil winding machine to form a secondary coil. The annular units are wound anticlockwise and clockwise. The counter-clockwise wound ring units are used as bottom and top units and a clockwise wound ring unit is used as a middle unit. Insulating spacers are added between the cells. Four turns of lower-number wire are wound as primary turns in the area of the annular subassembly where there is no secondary. The leads of the middle and lower ring units are coupled to each other, and the leads of the middle and upper ring units are also coupled to each other. The assembly is placed in a high temperature resistant plastic housing and encapsulated. In this configuration, the secondary voltage is a function of the primary current and the number of primary coil turns, the value of which is shown in fig. 3.

Although the invention has been described in considerable detail above, it will be understood that further modifications and variations can be made by those skilled in the art without strictly following this detailed description, all of which are intended to fall within the scope of the appended claims.

Claims (10)

1. A magnetic core-coil assembly for performing an ignition event in a spark-ignition internal combustion engine system having at least one combustion chamber, comprising:

a. the magnetic excitation device comprises a magnetic iron core made of ferromagnetic amorphous metal alloy, wherein the iron core is provided with a primary coil for low-voltage excitation and a secondary coil for high-voltage output;

b. the secondary coil comprises a plurality of iron core subassemblies which are simultaneously excited by a common primary coil;

c. each of the core subassemblies being adapted to generate, when energized, an additional secondary voltage that is delivered to the spark plug;

d. the core-coil assembly has the following capabilities: generating a high voltage in the secondary winding for a short period of time after excitation; and (ii) detecting a spark ignition condition within the combustion chamber to control the ignition event;

e. the core-coil assembly is encapsulated in a housing by a composite consisting of a two-component epoxy resin which is free of water and has sufficient strength to bond to the core-coil assembly, high temperature electrical properties, and excellent thermal shock resistance; and

f. the housing is made of a thermoplastic polyester, is adhesively fixed by the potting compound, is filled with glass fibers, and has a T-shape_gIs near the maximum operating temperature of the assembly, has a coefficient of thermal expansion matched to that of the epoxy, and is injection moldable.

2. The magnetic core-coil assembly of claim 1 wherein the magnetic core is fabricated by heat treating the ferromagnetic amorphous metal alloy.

3. The magnetic core-coil assembly of claim 1 wherein the magnetic core comprises a segmented core.

4. A magnetic core-coil assembly as claimed in claim 1, wherein the output voltage in the secondary winding is up to 10kV or more at a primary current of less than about 70 ampere-turns and up to 20kV in 25 to 150 microseconds at a primary current of 75 to 200 ampere-turns.

5. The magnetic core of claim 2, wherein the ferromagnetic amorphous metal alloy is ferrous based, and further comprising: metallic elements including nickel and cobalt; glass forming elements including boron and carbon; and semi-metallic elements including silicon.

6. A magnetic core-coil assembly as claimed in claim 1, including a plurality of individual subassemblies, each subassembly including an annularly wound portion with a secondary coil, the subassemblies being arranged to: the final assembly voltage is the sum of the subassembly voltages when driven by the common primary coil.

7. The magnetic core-coil assembly of claim 1 wherein the assembly has a bottom-up, segmented, stepped internal voltage distribution, the number of segments depending on the number of subassemblies.

8. A magnetic core-coil assembly for performing an ignition event in a spark-ignition internal combustion engine system having at least one combustion chamber, comprising:

a. the magnetic excitation device comprises a magnetic iron core made of ferromagnetic amorphous metal alloy, wherein the iron core is provided with a primary coil for low-voltage excitation and a secondary coil for high-voltage output;

b. the secondary coil comprises a plurality of iron core subassemblies which are simultaneously excited by a common primary coil;

c. the core subassemblies are adapted to produce, when energized, an additive secondary voltage that is delivered to the spark plug;

d. the core-coil assembly has the following capabilities: generating a high voltage in the secondary winding for a short period of time after excitation; and (ii) detecting a spark ignition condition within the combustion chamber to control the ignition event;

e. the core-coil assembly is enclosed within a housing by a composite comprised of a two-component elastomeric polyurethane material and having sufficient strength to bond to the core-coil assembly, high dielectric strength, moderate shore a hardness, and low dielectric constant; and

f. the housing is made of a flexible, high temperature-usable plastic, is adhesively secured by the potting compound, and has high dielectric strength, a low dielectric constant, excellent electrical properties and chemical resistance.

9. The magnetic core-coil assembly of claim 8 wherein the housing material is selected from the group of materials consisting of: polyether/polypropylene blends, polymethylpentene/polyolefin blends and polycycloolefin/polyolefin blends.

10. The magnetic core-coil assembly of claim 8 wherein the potting material is a silicone rubber based potting compound.